It was the first addressing mode to be widely deployed for public use. According to RFC 791, it was prepared for the Defense Advanced Research Projects Agency and it was designed for use in interconnected systems of packet-switched computer communication networks.
Since 1990's a fast growing concern of IPv4 address depletion has surfaces the public particularly Internet experts, developers, vendors and business sectors, seems to be the most influential of all.
In order to delay the inevitable shortage of the current IPv4 addresses, there were so many addressing mode (e.g. Network Address Translation, Supernetting) that has been devised to temporarily augment its life until a replacement which is IPv6 has propagated and effected to the Internet gateways, registries including regional and local providers and again business sectors.
A Pragmatic Report on IPv4 Address Space Consumption is available at Cisco Internet Protocol Journal issue on September 2005.